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Contraception options: the latest facts

Louise Cadman
BSc RGN
Senior Research Nurse/Family Planning Nurse
Cancer Research
UK
London

Between 2003 and 2004, 25% of women aged 16 to 49 chose the oral contraceptive pill, and 23% were using condoms as their contraceptive method.(1) Only 8% were using long-acting reversible contraception (LARC). Although condoms protect against sexually transmitted infections, contraceptively they have a comparatively high failure rate (5-15 per 100 woman-years).  The combined oral contraceptive pill (COC) is more effective (0.2-3 per 100 woman-years) but is unsuitable for many women, such as those at increased risk of deep vein thrombosis (DVT), smokers and women with a body mass index (BMI) greater than 30 (fourfold risk of a DVT).(2) There are alternatives to these methods. In 2005 the National Institute for Health and Clinical Excellence (NICE) issued guidelines for LARC.(1) The recommendations suggested an increase in the use of LARCs, which have fewer problems of user error or noncompliance. This not only would reduce the number of unplanned pregnancies but also would be more cost-effective.

Copper intrauterine devices

Mode of action
Intrauterine devices (IUDs) are T-shaped devices with around 380mm(2) of thin copper wire around a plastic frame. Copper ions are released into the uterus, creating an environment that is not conducive to fertilisation and implantation. IUDs affect sperm migration and generate a foreign body reaction within the uterus.

Efficacy, duration of use and indications
Failure rate is 0.3-2 per 100 woman-years. The most effective IUDs are those with more copper (380mm(2)).
IUDs can remain in situ for five to 10 years depending on the type. If an IUD is fitted in a woman over the age of 40, it does not need to be changed until after the menopause.(1)
IUDs are suited to those who want a contraceptive method that is independent of intercourse and where removal leads to immediate reversal.

Cautions and contraindications
Absolute contraindications include unexplained genital tract bleeding, Wilson's disease (a rare genetic disorder in which copper accumulates in the body, especially in the liver and brain, causing cirrhosis and brain damage), current pelvic infection, a distorted uterine cavity into which an IUD cannot be fitted, or known allergy to any component.

Risks and possible side-effects
IUDs can make periods longer, heavier and more painful. There is a slight increased risk of an ectopic pregnancy, but this is less than when no contraception at all is used.
In women at low risk of sexually transmitted infections (STIs), the risk of developing pelvic inflammatory disease (PID) following IUD insertion is very low (less than one in 100). NICE guidelines recommend screening for chlamydia trachomatis before insertion in women who are at risk of an STI.(1)
Complications, such as perforation and expulsion, are usually related to the insertion process.

Intrauterine systems

Mode of action and efficacy
Mirena (Schering Health Care) is a T-shaped device with a levonorgestrel-containing silastic capsule. It remains in the uterus, where it releases 20mg of levonorgestrel daily. The device is licensed for five years and works primarily by causing atrophy of the endometrium. Although it does suppress ovulation, the majority of women will ovulate at least occasionally. The failure rate is approximately 0.2 per 100 woman-years.

Indications
Mirena can reduce menstrual flow and dysmenorrhoea and is now licensed for use in women with menorrhagia. Evidence suggests that it may also provide symptomatic relief for women with small fibroids and endometriosis and is seen by some as a viable alternative to hysterectomy.(3,4)
Mirena is well suited to perimenopausal women requiring contraception. It has been licensed since October 2004 to provide the progestogen part of hormone replacement therapy (HRT), although in this situation it is currently only licensed for four years. 

Progestogen-only pills

Mode of action

Progestogen-only pills (POPs) thicken cervical mucus, making it impenetrable to sperm. The lining of the womb also undergoes thinning (endometrial atrophy), making implantation unlikely to occur. Second-generation POPs inhibit ovulation in 60% of cycles.(5) Cerazette (Organon), a newer, higher-dose POP (75µg desogestrel daily), has been shown to inhibit ovulation in 98% of cycles.(6)

Efficacy and indications
The efficacy of the second-generation POP is age-
related. Efficacy increases as female fertility declines with age. The failure rate in all women is close to one per 100 woman-years, but by the age of 40 its failure rate is only 0.57. POPs (excluding Cerazette) are therefore suited to women over the age of 30.Cerazette is better suited to younger women who wish to use the POP because it is more likely to inhibit ovulation. The POP is also of use to:

  • Women who cannot take oestrogen.
  • Women over the age of 35 who smoke.
  • Women who have diabetes or sickle cell disease.
  • Women who have become hypertensive or developed focal migraine while on the combined pill (COC).
  • Women who are breastfeeding (only a minute amount of the POP is released into the milk).

Cautions and contraindications
If there is a past or current history of a very high risk of severe arterial disease, extreme caution should be undertaken.
Any serious side-effect occurring in women on the COC, which cannot be clearly attributed to oestrogen, is also a contraindication to the POP. Obviously, the POP should not be given if there is a possibility of existing pregnancy.
Other contraindications include undiagnosed genital tract bleeding as the irregular bleeding pattern may confuse the picture.
Women who have had recent trophoblastic disease should not receive the POP until b-human chorionic gonadotrophin (b-HCG) levels are undetectable.
There is a very small increased risk of ectopic pregnancy in POP users. Since a woman with a previous history of ectopic pregnancy is already at increased risk of another, the POP should normally be avoided.

Side-effects
The main disadvantage of the POP is its tendency to cause irregular bleeding. Normal cycles are maintained in 40% of POP users, amenorrhoea in 20%, while 40% suffer irregular bleeding at variable intervals. Paradoxically, those who have regular cycles are at greatest risk of pregnancy on the POP as they are ovulating regularly.  Other side-effects are infrequent.  No association with carcinogenesis has been shown to date.  Interference with the follicular and luteal phases of the menstrual cycle in users is associated with the formation of ovarian cysts, which can cause pelvic pain.
   
Rules for taking the POP
The POP must be taken every day within the same three hours. Cerazette, however, has a 12-hour window. The POP should be started on day one of the cycle, with no need for additional precautions.
If a pill is more than three hours late, it should be taken immediately and then the next one taken on time. Under these circumstances, additional contraceptive precautions need to be used for 48 hours. The effect of progestogens on cervical mucus wears off within 27-36 hours but builds up again equally rapidly.
Broad-spectrum antibiotics have no effect on the POP. They do, however, interact with enzyme-inducing drugs. There is a suggestion (although no data) that in women who weigh over 70kg the efficacy of progestogen-only methods may be reduced and that two POPs a day should be given off licence.(7) This would seem to be unnecessary with Cerazette, since blood levels are higher.

Progestogen-only emergency contraception
Levonelle-2 (Schering Health Care) consists of two tablets equivalent to 25 Microval tablets (Wyeth).  Levonelle-2 is now licensed to be taken as a single stat dose with no effect on efficacy.(8)
Levonelle 1500, the single tablet version of Levonelle-2, has been available on prescription since November 2005. Levonelle One Step, also single dose, has been available to purchase over the counter since November 2004. 

Implants

Mode of action and efficacy
Implanon (Organon) is a subcutaneous progestogen- only implant. It consists of a single, silastic rod that releases 30-40µg of etonogestrel per day and lasts for three years. It is designed to achieve complete inhibition of ovulation, and to date, in clinical trials, there have been no pregnancies. Another implant contraceptive, Norplant, was discontinued in the UK in October 1999.

Rules for administering
Implanon is effective within 24 hours of insertion. It is introduced using an inserter the size of a blood transfusion needle and the procedure takes approximately two minutes. Removal, using a "pop-out" technique, takes approximately three minutes. Within a week of removal, blood levels of the hormone are undetectable.

Cautions and contraindications
The main side-effect is irregular bleeding, which tends to settle down after a few months; approximately 21% of users become amenorrhoeic. In June 2006 the recommendation for treating irregular bleeding while using a contraceptive implant was changed.(1) It should no longer be controlled with mifepristone (a synthetic steroid compound), which, although effective, is not licensed for this use. Mefenamic acid or ethinylestradiol should be offered.

Injectable progestogens
There are currently two injectable progestogen preparations in use: depot medroxyprogesterone acetate (DMPA or Depo-Provera [Pharmacia]) and norethisterone enanthate (Noristerat [Schering Health Care]). The former is given every 12 weeks, the latter every eight weeks. Of the two, DMPA is the most widely used and will therefore be referred to in this discussion.

Mode of action and efficacy
DMPA is a high-dose progestogen (150mg) given as a deep intramuscular (gluteal or deltoid) injection.  Progestogen is gradually released into the circulatory system and inhibits ovulation. The failure rate is low at 0.01-0.5 per 100 woman-years.

Indications
Injectable progestogens are suitable for women who cannot take oestrogen. They are also useful for women who forget pills or travel frequently.

Administration of DMPA
The injection is normally given in the first five days of the cycle, without the need for extra precautions. The injection site should not be rubbed, as this may affect the release of hormone.
Pregnancy has very rarely occurred at 14 weeks after the last injection. For this reason it is advised that pregnancy should be excluded if the injection interval is greater than 89 days, and extra precautions used for seven days.

Side-effects
Injectable progestogens can reduce menstrual symptoms such as menorrhagia, dysmenorrhoea and premenstrual symptoms. Because of the anovulatory action it is well suited to women with a history of ectopic pregnancy or ovarian cysts.

Cautions and contraindications
Once administered, the dose of hormones cannot be removed. This means that side-effects may have to be tolerated for three months. Disturbances of menstruation can occur, which may be marked and unpredictable. With repeated injections, however, women tend to become amenorrhoeic. Indeed, the majority are likely to achieve this within a year.
After stopping Depo-Provera, there is a median delay of fertility of 10 months. Women should be advised to have their last injection approximately six months before a planned pregnancy.
Weight gain may occur, and women who are prone to depression may complain of an increase in severity. 
A large WHO study published in 1991 showed a slightly increased risk of breast cancer within the first four years of use.(9)  This may be attributable to bias in the study. There has, however, been evidence to suggest a protective effect for endometrial cancer.
There has been discussion surrounding the risk of osteoporosis in Depo-Provera users. In November 2004 the Committee for the Safety of Medicines (CSM) issued advice on the use of Depo-Provera:(10)

  • Depo-Provera should only be used as the first-line contraception in adolescents if other methods have been discussed and considered unacceptable.
  • In any woman who wishes to continue use for longer than two years there should be a careful re-evaluation of the risks and benefits.
  • With significant risk factors for osteoporosis, other contraception should be considered.

Contraceptive patch
Evra (Janssen-Cilag), the contraceptive patch, contains 20µg of ethinylestradiol and 150µg of norelgestromin. It works in the same way as the COC by preventing ovulation. Although it contains a lower dose of oestrogen than the COC, it was recently observed that users are exposed to about 60% more of the oestrogen component than they would be with some COCs.(11)  Each patch is worn for a week and can be placed on the buttocks, abdomen, the back or the upper arm, and the adherence is apparently not affected by showering, bathing or swimming. The main side-effect in clinical trials was transient breast tenderness in the first couple of months. Compliance has been shown to be better than with the COC or POP.(12)

The male contraceptive
The aim of male contraceptives has been to switch off sperm production in much the same way as the ovaries are inhibited in women. Reducing the sperm count to zero has proven problematic, although a study in Australia in 2003 showed that a combination of a testosterone implant and three-monthly injections of progestin was 100% effective. In addition, studies have been particularly difficult to conduct due to the reluctance of men to take part; some reported side-effects included shrunken testicles and acne. More optimistically, a recent international study reported that two-thirds of men would be prepared to take a male pill if available, and all the women said they would trust their partner to do so. Unfortunately, for most of the last 10 years we have been told that a male hormonal contraceptive is only a few years away and so it is simply a matter of waiting patiently.

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References

  1. National Institute for Clinical Excellence. Long acting reversible contraception. Clinical Guideline 30. London: NICE; 2005. Available from: http://www.nice.org.uk/CG030
  2. Szarewski A. Contraception and vascular disease. Gynaecol Forum 2005;10:23-5.
  3. Grigorieva V, Chen-Mok M, Tarasova M, Mikhailov A. Use of a levonorgestrel-releasing intrauterine system to treat bleeding related to uterine leiomyomas.Fertil Steril 2003;79:1194-8.
  4. Lockhat EB, Emembolu JO, Konje JC. The evaluation of the effectiveness of an intrauterine-administered progestogen (levonorgestrel) in the symptomatic treatment of endometriosis and in the staging of the disease. Hum Reprod 2004;19(1):179-84.
  5. Rice CF, Killick SR, Dieben T, Coelingh Bennink H. A comparison of the inhibition of ovulation achieved by desogestrel 75 micrograms and levonorgestrel 30 micrograms daily.  Hum Reprod 1999;14:982-5.
  6. Korver T, for collaborating group. A double blind study comparing contraceptive efficacy, acceptability and safety of two progestogen-only pills containing desogestrel 75mcg/day or levonorgestrel 30mcg/day. Eur J Contracept Reprod Health Care 1998;3:169-78.
  7. Vessey M. Oral contraceptive failures and body weight: findings in a large cohort study. J Fam Plann Reprod Health Care 2001;27(2):90-1.
  8. Von Hertzen H, Piaggio G, Ding J, et al. Low dose mifepristone and two regimens of levonorgestrel for emergency contraception: a WHO multicentre randomised trial.Lancet 2002;360: 1803-10.
  9. Breast cancer and depot-medroxyprogesterone acetate:a multinational study. WHO Collaborative Study of Neoplasia and Steroid Contraceptives. Lancet 1991;338:833-8.
  10. MHRA statement on Depo Provera, 18 November 2004. Available from:  http://www.mhra.gov.uk
  11. Weisberg E. Ortho Evra contraceptive patch. IPPF Med Bull 2006;40(1):3-4.
  12. Archer DF, Bigrigg A, Smallwood GH, Shangold GA, Creasy GW, Fisher AC. Assessment of compliance with a weekly contraceptive patch (Ortho EVRA/EVRA) among North American women. Fertil Steril 2002:77 Suppl 2:27-31.